Nine people are dead and nearly three dozen more remain hospitalized after being found in the back of a sweltering tractor-trailer in San Antonio early Sunday morning in what officials describe as an immigrant-smuggling operation gone wrong. (Published Monday, July 24, 2017)

Ten people are dead and nearly three dozen more remain hospitalized after being found in the back of a sweltering tractor-trailer in San Antonio early Sunday morning in what officials describe as an immigrant-smuggling operation gone wrong.

U.S. officials say 17 people pulled from the trailer suffered life-threatening injuries.

San Antonio Chief of Police William McManus and Fire Chief Charles Hood confirmed overnight police arrived at a Walmart on the city's southwest side shortly after midnight to find eight people dead and dozens of others, including men, women and children, suffering from heat stroke or dehydration and in need of immediate medical care after being trafficked into the United States.

"We're looking at a trafficking crime here this evening. The Department of Homeland Security is involved; homicide will work with them to determine the origin of this horrific tragedy," McManus said.

One of the people hospitalized died Sunday and another was reported deceased Monday morning. Another victim was found in a field nearby, bringing the total number of people found to 39. All of the survivors that have been located are receiving medical care.

McManus said early Sunday morning police were called after a passenger in the truck asked a Walmart employee for water. The employee then saw a number of people in the back of the truck and called for help.

Many of the survivors had heart rates over 130 beats per minute and were hot to the touch, Hood said. They had no water and the air conditioning in the truck was broken. The least-severe cases just needed to be re-hydrated.

It's not clear how long the people had been in the truck or how long they had been without air conditioning and water. Authorities said they were investigating where the immigrants were from.

Hood said EMS transported patients ranging in age from young children to adults in their 30s to seven different area hospitals, sending a large number downtown.

Police said while reviewing the store's surveillance video they noticed a number of cars had arrived at the store and left with some of the survivors. The store's surveillance video is part of the ongoing investigation, McManus said.

Hours later, after daybreak, a helicopter hovered over the area, and investigators were still gathering evidence from the tractor-trailer, which had an Iowa license plate and was registered to Pyle Transportation Inc. of Schaller, Iowa. The company did not immediately respond to a phone message seeking comment.

"This is not an isolated incident. This happens quite frequently. Fortunately, we came across this one," McManus said. "And fortunately there are people that survived."

McManus said truck driver James Mathew Bradley Jr., who remained at the scene and is in police custody, is expected to face state and federal charges. The survivors, McManus said, will be investigated by Immigration and Customs Enforcement.

Federal authorities say charges will be filed against Bradley, 60, from Clearwater, Florida. Bradley is being held in federal custody in connection with this incident, NBC News reported. He is expected to make a court appearance after a criminal complaint is filed Monday.

On Sunday, Texas Gov. Greg Abbott released a statement saying, “Human trafficking is an epidemic that Texas is working to eradicate. To that end, Texas will continue to provide protection for the victims who have been robbed of their most basic rights, and bring down the full weight of the law for the perpetrators of this despicable crime.”

Also on Sunday, San Antonio-based U.S. Attorney Richard Durbin Jr. said those responsible for the deaths are "ruthless human smugglers indifferent to the well-being of their fragile cargo."

Durbin also said federal investigators will work with San Antonio police to identify those responsible.

"By any standard, the horrific crime uncovered last night ranks as a stark reminder of why human smuggling networks must be pursued, caught and punished," Thomas Homan, acting director of U.S. Immigration and Customs Enforcement, said in a statement.

The temperature Saturday in San Antonio reached 104 degrees and the heat index was likely closer to 110. Temperatures inside a vehicle can increase by 20 degrees more than the outside temperature in as little as 10 minutes, after an hour that temperature can be 43 degrees higher. Heat stroke can be fatal at when the body reaches 107 degrees.

Sunday's Tragedy Just the Latest Case of Human Smuggling to End in Deathz

In the May 2003 case, the immigrants were being taken from South Texas to Houston. Prosecutors said the driver heard them begging and screaming for their lives but refused to free them. The driver was sentenced to nearly 34 years in prison.

The Border Patrol has reported at least four truck seizures this month in and around Laredo, Texas. On July 7, agents found 72 people crammed into a truck with no means of escape, the agency said. They were from Mexico, Ecuador, Guatemala and El Salvador.

Authorities in Mexico have also made a number of such discoveries over the years.

Last December, they found 110 migrants trapped and suffocating inside a truck after it crashed while speeding in the state of Veracruz. Most were from Central America, and 48 were minors. Some were injured in the crash.

Last October, also in Veracruz state, four migrants suffocated in a truck carrying 55 people.

Editor's Note: A previous version of this story incorrectly reported the death toll and number of people found in the truck. This story has been updated to reflect the death toll of nine that was confirmed by the Immigration and Customs Enforcement. Authorities also confirmed that 39 people were found in the truck. Of the nine deceased, are all adult males, according to The United States Attorney's Office for the Western District of Texas.